7.(a) An engineer designs a satellite dish with a parabolic cross-section.
The dish is 15 feet wide at the opening and the depth is 4feet.
Find the position of the light source (the focus). How far is it from the deepest part of the
dish? (3)
(b) The outer door of an airplane hangar is in the shape of a parabola. The door is 120 feet
wide and 90 feet high.
(i) Find the equation describing the door’s shape. (3)
(ii) If you are 6 feet tall, how far must you stand from the edge of the door to
keep from hitting your head